1. Field of the Invention
The present invention relates to a vehicle brake hydraulic pressure control system including a hydraulic pressure generating source which outputs hydraulic pressure in response to operation of a brake pedal, wheel brakes which operate by the action of hydraulic pressure, a hydraulic pressure control unit which has a pump driven by an electric motor and a normally open solenoid valve interposed between a hydraulic pressure path to which a discharge side of the pump is connected and the hydraulic pressure generating source and which is interposed between the wheel brakes and the hydraulic pressure generating source in such a manner as to adjust hydraulic pressures at the wheel brakes, brake hydraulic pressure detecting unit which detects hydraulic pressures at the wheel brakes, and a controller which includes a target wheel brake pressure setting unit for setting target hydraulic pressures for the wheel brakes for controlling the operation of the hydraulic pressure control unit so that the hydraulic pressures at the wheel brakes become target hydraulic pressures set by the target wheel brake pressure setting unit.
2. Description of Related Art
A vehicle brake hydraulic pressure control system like this has already been known in, for example, Japanese Patent Unexamined Publication No. JP-A-2004-196235.
Incidentally, in a brake hydraulic pressure control system like this, hydraulic pressures built up in the wheel brakes can be controlled by adjusting the hydraulic pressure in the hydraulic pressure path which is connected to the discharge side of the pump by driving the pump by the electric motor and controlling the normally open solenoid valve, which is interposed between the hydraulic pressure path and the hydraulic pressure generating source, to open or close in such a state that no hydraulic pressure is outputted from the hydraulic pressure generating unit. As this occurs, although it is considered to increase the controlled variable of the normally open solenoid valve in order to enhance response and toughness with respect to disturbance, in the event that the controlled variable of the normally open solenoid valve is increased in such a state that the discharge pressure of the pump is not built up sufficiently at an initial stage of the control, an overshoot is generated when the discharge pressure of the pump has reached a predetermined value.